JP2008275761A - Liquid crystal display device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-definition transflective liquid crystal display device achieving wide viewing angle with a retardation plate incorporated in a reflective display part. <P>SOLUTION: The liquid crystal display device includes the reflective display part and a transmissive display part. A built-in retardation layer is provided between a first substrate and a second substrate. As a forming material of the retardation layer 38 formed on a major surface of the first substrate 31, a liquid crystal monomer with acrylate with photopolymerization initiator having a phosphine oxide structure added thereto is used. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device capable of reflective display in a wide range of environments including a bright place to a dark place and capable of high-quality transmissive display with a wide viewing angle and a method for manufacturing the same.

  Currently, transmissive liquid crystal display devices with a wide viewing angle, such as the IPS (In Plane Switching) method and the VA (Vertical Alignment) method, are widely used as monitors for various devices, and are used as televisions with improved response characteristics. Yes. On the other hand, liquid crystal display devices are widely used in portable information devices such as mobile phones and digital cameras. Portable information devices are mainly used by individuals, but recently, the number of display units with variable angles is increasing, and a wide viewing angle is desired because they are often observed from an oblique direction.

  A display device for a portable information device is used in various environments including outdoors from a sunny day to a dark room, and thus it is desired to be a transflective type. The transflective liquid crystal display device has a reflective display portion and a transmissive display portion in one pixel.

  The reflective display unit reflects and displays light incident from the surroundings using a reflector, and the contrast ratio is constant regardless of the surrounding brightness, so it is a relatively bright environment from outdoor to indoors in fine weather. Good display is obtained below. On the other hand, the transmissive display unit uses a backlight and has a constant luminance regardless of the environment, so that a display with a high contrast ratio can be obtained in a relatively dark environment from indoors to a dark room. A transflective liquid crystal display device having both of these characteristics can display with a high contrast ratio in a wide range of environments including the outdoors from a sunny day to a dark room.

  Conventionally, it has been expected that a reflective display and a transmissive display with a wide viewing angle can be obtained at the same time if the IPS system known for the transmissive display with a wide viewing angle is made a transflective type. For example, Patent Document 1 describes a transflective IPS system.

  In the transflective IPS type liquid crystal display device, retardation plates are arranged on the entire upper and lower outer surfaces of a liquid crystal panel in which a liquid crystal layer is sealed between two transparent substrates. However, because the retardation plate has a viewing angle dependency, even if the phase difference and the axial arrangement of the liquid crystal layer and the plurality of retardation plates are optimized in the normal direction of the liquid crystal layer, the darker as the distance from the normal direction increases. Rapidly deviates from optimal conditions for display.

  The viewing angle dependence of the retardation plate can be reduced by adjusting the refractive index in the thickness direction of the retardation plate, but cannot be completely eliminated. As a result, in the transflective IPS system, the increase in dark display transmittance in the viewing angle direction is large, and the viewing angle characteristics of the transmissive display are lower than in the transmissive IPS system.

  Non-Patent Document 1 discloses an installation structure and display characteristics when a retardation plate (retardation layer) is built in the panel instead of an externally installed retardation plate.

In Patent Document 2, in the VA method, the retardation layer is disposed so as to be close to the liquid crystal layer, and is patterned and disposed only on the reflective display portion. However, application to the IPS system that gives a wide viewing angle transmission display is not considered. Japanese Patent Application Laid-Open No. 2004-133867 discloses a consideration for setting a transflective IPS system having a built-in retardation layer to have a wide viewing angle equivalent to that of the transmissive IPS system.
Japanese Patent Laid-Open No. 11-242226 JP 2003-279957 A JP 2005-338256 A c. Doornkamp et al. , Philips Research, “Next generation mobile LCDs in-cell retarders.” International Display Worksshops 2003, p685 (2003).

  In the transmissive IPS system, the liquid crystal layer is homogeneously aligned, and polarizing plates (upper and lower polarizing plates) installed on the outer surfaces of the first substrate and the second substrate are arranged so that the transmission axes are orthogonal to each other, and One of the transmission axes is parallel to the alignment direction of the liquid crystal layer. The light incident on the liquid crystal layer is linearly polarized light, and its vibration direction is parallel to the alignment direction of the liquid crystal layer, so that no phase difference is given by the liquid crystal layer. As a result, a dark display with a low transmittance can be realized, and since no retardation layer (retardation plate) is interposed between the liquid crystal layer and the polarizing plate, no extra phase difference occurs in the viewing angle direction, and a dark display with a wide viewing angle is achieved. realizable. As described above, the transmission type IPS method essentially does not require a retardation layer (retardation plate).

  A transflective liquid crystal display device has a reflective display portion and a transmissive display portion, which have substantially different optical conditions for dark display, in one pixel. That is, in the reflective display unit, light enters the polarizing plate on the substrate (first substrate) side of the upper surface of the liquid crystal panel constituting the liquid crystal display device, is reflected by the reflective plate inside the liquid crystal panel, and then again. It passes the polarizing plate on the upper surface and heads for the user. On the other hand, in the transmissive display unit, light enters from a polarizing plate on the substrate (second substrate) side on the lower surface of the liquid crystal panel, and then passes through the polarizing plate on the upper surface of the liquid crystal panel and travels toward the user.

  Due to such a difference in optical path, the phase difference of light that is darkly displayed differs between the reflective display portion and the transmissive display portion by a quarter wavelength. For this reason, when the reflective display portion is bright, the transmissive display portion is dark, or vice versa, and the reflective display portion and the transmissive display portion have different applied voltage dependencies. In order to make them dependent on the same applied voltage, the phase difference between the reflective display portion and the transmissive display portion must be shifted by a quarter wavelength by some method.

  In the conventional transflective IPS system, retardation plates are arranged on the entire surface (outer surface) above and below the liquid crystal panel. Among these, the retardation plate on the upper side (first substrate side) of the liquid crystal panel is light incident on the reflective display portion from the outside, light reflected by the reflective plate of the reflective display portion, and light that has passed through the transmissive display portion. Pass through. As described above, the upper retardation plate acts on both the reflective display unit and the transmissive display unit. On the other hand, the phase difference plate on the lower side (second substrate side) of the liquid crystal panel acts only on the transmissive display unit because only the light source light incident on the transmissive display unit passes therethrough. By utilizing the difference in the action of the upper and lower phase plates with respect to the reflective display portion and the transmissive display portion, the phase difference between them is shifted by a quarter wavelength. However, when the retardation plate is interposed between the liquid crystal layer and the polarizing plate, an extra phase difference is generated in the viewing angle direction, and the viewing angle characteristics of dark display are deteriorated.

  Further, in the transflective IPS system in which the function of a retardation plate as disclosed in Patent Document 3 is incorporated in a liquid crystal panel to form a retardation layer, the retardation layer is formed only on the reflective display portion. For the formation of the retardation layer, patterning using a photolithography method in which a retardation layer-forming material mainly composed of a liquid crystal monomer with acrylate is applied and exposed to a photomask is employed.

  The retardation layer forming material contains a polymerization initiator. However, this polymerization initiator tends to excessively react with exposure, and when the excessive reaction occurs, the pattern width of the cured retardation layer is significantly larger than the design value. It becomes thicker and protrudes to the transmissive display portion, degrading the transflective display characteristics. This cannot meet the demand for high definition (nominal 2 inches, pixel number 640 × 480 (VGA)). Further, when the pattern width of the retardation layer is increased, the alignment tolerance between the substrate and the mask during exposure in the manufacturing process is reduced.

  An object of the present invention is to form a retardation layer so that good display characteristics can be obtained in a liquid crystal display device incorporating a retardation layer. In other words, by forming the retardation layer within the tolerance of the designed pattern with respect to the reflective display part, the degradation of the transflective display characteristic is suppressed, and the wide viewing angle equivalent to the transmissive type is obtained. An object is to provide a transflective liquid crystal display device that can be realized.

  The cause of the excessive reaction of the phase difference layer forming material seems to be that the radical sequential reaction proceeds excessively and excessive curing occurs during pattern exposure.

  Therefore, in the present invention, an acrylate-attached liquid crystal monomer to which a photopolymerization initiator having a phosphine oxide structure having a gentle radical emission is added is used as a retardation layer forming material.

  The present invention is, for example, a liquid crystal display device having a reflective display portion and a transmissive display portion, and is sandwiched between a first substrate, a second substrate, the first substrate, and the second substrate. Liquid crystal layer and a retardation layer built in between the first substrate and the second substrate, and the retardation layer has a liquid crystal monomer with an acrylate and starts photopolymerization having a phosphine oxide structure It is formed by polymerization using an agent.

  In the case of a transflective IPS liquid crystal display device, a retardation plate (retardation layer) is disposed only on the reflective display portion, and the polarizing plate has a specification common to the reflective display portion and the transmissive display portion. The polarizing plate is disposed on the entire upper and lower surfaces of the first substrate and the second substrate constituting the liquid crystal panel, and the retardation plate is a built-in retardation layer (in this case, the retardation layer is a sealing material). It is desirable to dispose it on the inner display area side excluding the portion facing the first substrate). The built-in retardation layer is formed only on the reflective display portion. At this time, by arranging the upper and lower polarizing plates in the same manner as in the transmissive IPS system (the transmission axes are orthogonal and one of them is parallel to the liquid crystal alignment direction), the same transmissive display viewing angle characteristics as in the transmissive IPS system are realized.

  The built-in retardation layer is arranged so that the polarizing plate is arranged in the same manner as in the transmissive IPS system, and the phase difference between the reflective display portion and the transmissive display portion is shifted by a quarter wavelength. Specifically, a laminated body of a liquid crystal layer and a built-in retardation layer is arranged in a broadband quarter-wave plate. That is, the retardation closer to the reflector is set to a quarter wavelength, and the other is set to a half wavelength.

  In the IPS mode, when a voltage is applied, the liquid crystal layer changes its orientation mainly so that the direct orientation rotates within the layer, the change of the tilt angle is small, and the retardation hardly changes. Therefore, the liquid crystal layer of the liquid crystal layer and the retardation layer is disposed so as to be close to the reflective electrode, and the retardation is set to a quarter wavelength.

  The slow axis of the built-in retardation layer is determined as follows. That is, the azimuth angle is defined counterclockwise with the upper polarizing plate transmission axis as 0 degree. When the slow axis azimuth angle of the retardation layer is θPH and the azimuth angle of the alignment direction of the liquid crystal layer is θLC, the azimuth angle when a broadband quarter-wave plate is obtained is expressed by the following equation (1). .

          2θPH = ± 45 ° + θLC (1)

  Here, θLC must be set to 0 ° or ± 90 ° because the polarizing plate arrangement in the transmissive display portion is the same as that of the transmissive IPS. From this, θPH is ± 22.5 degrees (20 ° to 25 ° with a manufacturing margin of ± 10%) or ± 67.5 ° (60 ° to 75 ° with a manufacturing margin of ± 10%) Become. By arranging the laminated layer of the liquid crystal layer and the built-in retardation plate (retardation layer) in a broadband quarter-wave plate, the reflectance is reduced over the entire visible wavelength range, and the low reflectance and no A colored reflective display is obtained.

  The reflective display unit and the transmissive display unit have different optimum values of the liquid crystal layer retardation for setting the reflectance and transmittance to the limit values determined by the light absorption of the polarizing plate. In the display unit, the wavelength is ½. In order to realize this, the thickness of the liquid crystal layer of the reflective display portion must be smaller than that of the transmissive display portion. Specifically, a layer thickness adjusting layer is arranged in the reflective display portion, and the layer thickness of the liquid crystal layer of the reflective display portion is reduced by the thickness of the layer thickness adjusting layer. The layer thickness adjusting layer must be disposed so as to correspond to the reflective display portion.

  In the present invention, the retardation plate is incorporated in the form of a retardation layer as a retardation plate, and this built-in retardation layer is disposed at a position corresponding to the reflective display portion. The difference in retardation required for the reflective display portion and the transmissive display portion is a quarter wavelength, and the retardation required for the built-in retardation layer is a half wavelength.

  Therefore, if the birefringence of the built-in retardation layer is more than twice that of the liquid crystal layer, the layer thickness of the retardation layer is smaller than the difference in thickness between the liquid crystal layers required for the reflective display portion and the transmissive display portion. . In this case, the retardation layer and the layer thickness adjusting layer are laminated and patterned so as to correspond to the reflective display portion, and the total thickness of both layers is required for the reflective display portion and the transmissive display portion. What is necessary is just to make the layer thickness difference of a layer.

  Alternatively, if the birefringence of the retardation layer is twice that of the liquid crystal layer, the thickness of the built-in retardation layer is equal to the difference in thickness between the liquid crystal layers required for the reflective display portion and the transmissive display portion. In this case, since the layer thickness adjusting layer is unnecessary, the manufacturing process can be simplified.

  Embodiments to which the present invention is applied will be described below with reference to the drawings.

  << First Embodiment >>

  FIG. 1 is a plan view illustrating a configuration example of one pixel of a liquid crystal panel constituting the liquid crystal display device to which the first embodiment is applied. FIG. 2 is a cross-sectional view taken along the line A-A ′ of FIG. 1 for explaining a schematic configuration example of one pixel of the liquid crystal panel shown in FIG. 1.

  The liquid crystal panel includes a first substrate 31, a liquid crystal layer 10, and a second substrate 32, and the liquid crystal layer 10 is held in a facing gap between the first substrate 31 and the second substrate 32. .

  On the main surface (inner surface) of the first substrate 31, a color filter 45 partitioned by a black matrix 35, a planarization layer (first protective film) 36, and a third alignment film (built-in retardation layer) Alignment film) 37, a built-in retardation layer (hereinafter simply referred to as retardation layer) 38, a protective layer (second protective film) 40 of the retardation layer 38, and a first alignment film 33. They are stacked in order.

  However, the retardation layer 38 is disposed only in the transmissive display portion RA, and is not disposed in the transmissive display portion TA.

  The third alignment film 37 is provided with an alignment control ability for controlling the alignment of the forming material of the retardation layer 38 made of the liquid crystal layer composition. Further, the first alignment film 33 is provided with an alignment control ability for controlling the initial alignment of the liquid crystal layer 10 for controlling display light.

  The main surface of the second substrate 32 has a thin film transistor TFT for driving a pixel. The thin film transistor TFT is connected to the scanning wiring 21, the signal wiring 22, and the pixel electrode 28.

  In addition, a common wiring 23 and a common electrode 29 are provided. Here, the thin film transistor TFT has an inverted staggered structure, and its channel portion is formed of an amorphous silicon (a-Si) layer 25. The scanning wiring (gate) 21 and the source / drain electrode 24 are insulated by a first insulating layer 51. A second insulating layer 52 is on the thin film transistor TFT.

  The scanning wiring 21 and the signal wiring 22 intersect in the row direction and the column direction to form a two-dimensional matrix. The thin film transistor TFT is generally located near the intersection.

  The common wiring 23 is arranged in parallel with the scanning wiring 21 and is connected to the common electrode 29 through the second through hole 27. The pixel electrode 28 and the source / drain electrode 24 of the thin film transistor TFT are coupled by a first through hole 26. On the pixel electrode 28, there is a second alignment film 34, which is provided with an alignment control ability for controlling the initial alignment of the liquid crystal layer 10.

  The first substrate 31 is preferably made of borosilicate glass with few ionic impurities and has a thickness of, for example, 0.5 mm. The color filter 45 partitioned by the black matrix 35 has red, green, and blue portions (color subpixels) arranged repeatedly in a stripe pattern, and each stripe is parallel to the signal electrode 22. The unevenness of the formation surface of the black matrix 35 and the color filter 45 is flattened by a resinous flattening layer (first protective film, overcoat film) 36. The first alignment film 33 is a polyimide organic film and is subjected to an alignment process by a rubbing method.

  The second substrate 32 is suitably borosilicate glass similar to the first substrate 31 and has a thickness of 0.5 mm, for example. Similar to the first alignment film 33, the second alignment film 34 is a horizontally oriented polyimide organic film. The signal wiring 22, the scanning wiring 21, and the common wiring 23 are formed of aluminum (Al), an alloy thereof (alloy of aluminum and neodymium: Al—Nd), chromium (Cr), or the like. A transparent conductive film such as indium tin oxide (indium tin oxide: ITO) is desirable, and the common electrode 29 is desirably formed of a transparent conductive film such as ITO.

  The pixel electrode 28 has slits 30 parallel to the scanning wiring 21 and the pitch of the slits 30 is about 4 μm. The pixel electrode 28 and the common electrode 29 are separated by a third insulating layer 53 having a layer thickness of 0.5 μm, and an electric field is formed between the pixel electrode 28 and the common electrode 29 when a voltage is applied. The electric field is distorted in an arch shape due to the influence of the third insulating layer 53 and passes through the liquid crystal layer 10. As a result, an orientation change occurs in the liquid crystal layer 10 when a voltage is applied. In addition, said numerical value is an example including the other numerical value by this specification and drawing, and this invention is not limited to this numerical value.

  The common wiring 23 has a structure protruding into the pixel electrode 28 at a portion intersecting with the pixel electrode 28. In FIG. 1, a portion where the common wiring 23 overlaps with the pixel electrode 28 is a reflective display portion RA, and reflects light as indicated by reflected light 62. In other overlapping portions of the pixel electrode 28 and the common electrode 29, as shown by the transmitted light 61, the backlight light passes and becomes the transmissive display portion TA. Since the optimal layer thickness of the liquid crystal layer is different between the transmissive display portion TA and the reflective display portion RA, a step is generated at the boundary. In order to shorten the boundary between the transmissive display portion TA and the reflective display portion RA, the transmissive display portion TA and the reflective display portion RA are arranged so that the boundary is parallel to the short side of the pixel.

  Thus, if the wiring such as the common wiring 23 is also used as a reflector, an effect of reducing the manufacturing process can be obtained. If the common wiring 23 is made of aluminum having a high reflectance, a brighter reflective display can be obtained. The same effect can be obtained even if the common wiring 23 is made of chromium and a reflector made of aluminum or silver alloy is separately formed.

  The liquid crystal layer 10 is a liquid crystal layer composition exhibiting positive dielectric anisotropy in which the dielectric constant in the alignment direction is larger than that in the normal direction. Here, the birefringence is 0.067 at 25 ° C., and shows a nematic phase in a wide temperature range including a room temperature region. In addition, during a holding period when driving at a frequency of 60 Hz using a thin film transistor, a high resistance value that does not cause flicker by sufficiently holding reflectance and transmittance is exhibited.

  Next, a manufacturing process of the liquid crystal panel configured as described above will be described with reference to FIG.

  First, the black matrix 35 and the color filter 45 are formed on the main surface of the first substrate 31, and the surfaces thereof are covered with the first protective film 36 and planarized (P-1). On the first protective film 36, an alignment film (third alignment film) 37 for retardation layer is applied and rubbed to give alignment control ability (P-2). The third alignment film 37 is horizontally oriented and has a function of determining the slow axis direction of the retardation layer 38.

  Next, a retardation layer forming material is applied on the third alignment film 37 (P-3). The retardation layer forming material needs to be appropriately selected in order to prevent coloring of the retardation layer 38 and to prevent “overweight” due to excessive (rapid) polymerization reaction.

  In this embodiment, as a retardation layer forming material, a photopolymerization initiator having a phosphine oxide structure in a nematic liquid crystal monomer having a photoreactive acrylic group (acrylate) at the molecular end (referred to as “liquid crystal monomer with acrylate”). An organic material in which one kind or two or more kinds (reaction initiator) is dispersed in an organic solvent is used.

  What is necessary is just to select suitably the liquid crystal monomer with an acrylate according to required (DELTA) n. Examples of liquid crystal monomers with acrylate are shown in the following “Chemical Formula 1” and “Chemical Formula 2”.

  By appropriately selecting the liquid crystal monomer with acrylate, the photopolymerization initiator, and the wavelength of the light to be irradiated, coloring of the formed retardation layer 38 is suppressed, and the “thickening” of the retardation layer 38 due to overpolymerization. Can be prevented.

  In this embodiment, a phosphine oxide photopolymerization initiator is used. By using a phosphine oxide-based photopolymerization initiator, the transmittance of the retardation layer 38 can be in a range of 95% or more with respect to visible light (visible light, for example, light having a wavelength in the range of 400 nm to 800 nm). And coloring can be suppressed.

  Further, if a phosphine oxide photopolymerization initiator is used, excessive polymerization of the liquid crystal monomer is suppressed, and “thickening” of the retardation layer 35 can be prevented.

  Examples of polymerization initiators having a phosphine oxide structure in the following “Chemical Formula 3” include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis (2 , 6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide. These can be purchased as Irgacure 819, Darocur TPO, and Irgacure 1800 (1870) from Ciba Specialty Chemicals, respectively.

  It is effective to add 0.01 to 0.3% of a leveling agent to the retardation layer forming material for the purpose of improving wettability. As a leveling agent, for example, BYK-302, BYK-306, BYK-307, BYK-330, BYK-352, BYK-354, BYK-356, BYK-361N, BYK-370N, BYK-390, manufactured by BYK Japan Tego's Flow 300, Flow 425, Flow ZFS 460, Glide 100, Glide 410, Glide 420, Glide 435, Glide A 115, Glide ZG 400, and the like can be used.

  As the organic solvent, propylene glycol monomethyl ether acetate, cyclohexanone, ethylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, methoxybutyl acetate, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether and the like can be used.

  After applying the retardation layer forming material, the solvent is removed by prebaking for 2 to 3 minutes using a hot plate at 100 ° C. (P-4). Thereby, a transparent film is formed. This film is oriented in the direction of the orientation treatment of the third orientation film 37 when pre-baked, and has a function as a retardation plate.

  The pre-baked retardation layer forming material is irradiated with ultraviolet light to a portion corresponding to the reflective display portion RA using an exposure mask having an opening corresponding to the pattern of the retardation layer 38 to photopolymerize the acrylic group. And cured to form the retardation layer 38 (P-5). By this mask exposure, the acrylate corresponding to the opening of the exposure mask is polymerized to form a film insoluble in the organic solvent. At this time, the film concentration is adjusted by appropriately adjusting the solution concentration and the coating conditions at the time of coating so that the retardation of the retardation layer 38 becomes a half wavelength at a wavelength of 550 nm.

  Thereafter, development with an organic solvent is performed to remove unexposed portions (P-6).

  Next, a transparent organic layer is applied on the retardation layer 38 to form the second protective layer 40 (P-7). Further, the film thickness adjusting layer 39 is formed only on the upper layer of the retardation layer 38 (P-8). Specifically, first, a photosensitive transparent resist is applied to the second protective layer 40 and exposed to ultraviolet rays using an exposure mask. Here, patterning is performed using an exposure mask having a distribution similar to that of the reflective display area RA. Thereafter, when alkali development is performed, the film thickness adjusting layer 39 is formed only on the retardation layer 38.

  Here, the reason for providing the film thickness adjusting layer 39 is as follows. If the retardation layer 38 has a Δn larger than twice that of the liquid crystal layer, the thickness becomes insufficient when the retardation of the retardation layer 38 is ½ wavelength. The difference in retardation between the reflective display portion TA and the transmissive display portion RA is smaller than a quarter wavelength. Therefore, by forming a film thickness adjusting layer 39 on the retardation layer 38, a quarter-wave retardation difference is ensured between the reflective display portion and the transmissive display portion.

  Next, the first alignment film 33 is applied to the uppermost layer of the main surface of the first substrate 31, and the second alignment film 34 is applied to the uppermost layer of the main surface of the second substrate 32, and cross each other at a predetermined angle. After rubbing in such a direction, columnar spacers are interposed in the display areas of the first substrate 31 and the second substrate 32 (P-9), and a sealant is applied to the inside of the outer peripheral edge to attach both substrates. Then, the liquid crystal layer 10 is sealed inside (P-10).

  Finally, the first polarizing plate 41 and the second polarizing plate 42 are respectively arranged outside the first substrate 31 and the second substrate 32 (P-11). Here, the transmission axes of the first polarizing plate 41 and the second polarizing plate 42 are arranged so as to be orthogonal and parallel to the alignment direction of the liquid crystal layer, respectively.

  The liquid crystal panel manufacturing process has been described above.

  In the liquid crystal panel, the light diffusive pressure-sensitive adhesive layer 43 in which a large number of transparent microspheres having a refractive index different from that of the pressure-sensitive adhesive material is mixed is used for the pressure-sensitive adhesive layer 43 of the first polarizing plate 41. . With such a configuration, the optical path of incident light is expanded by utilizing the effect of refraction caused by the difference in refractive index between the adhesive material and the microsphere. Thereby, it is possible to reduce iridescent coloring caused by interference of reflected light between the pixel electrode 28 and the common electrode 29. However, the configuration of the adhesive layer 43 is not limited to this, and it goes without saying that an adhesive material without microspheres may be used.

  When a retardation layer forming material to which a phosphine oxide photopolymerization initiator is added is used as in this embodiment, the pattern width of the retardation layer 38 is about 3-5 μm thicker than the design value of the width of the mask opening. To be suppressed. Therefore, it is possible to make the pattern width maximum detail 20 μm or less. Then, the reproducibility of the photomask is improved, and high definition of the liquid crystal panel can be realized. Further, in the manufacturing process, the tolerance of the alignment accuracy at the time of pattern exposure is increased, and product defects due to the exposure misalignment are reduced.

  Here, the usefulness of the phosphine oxide photopolymerization initiator will be described using a comparative example. In the comparative example, as shown in “Chemical Formula 4” below, a general-purpose photopolymerization initiator, for example, Irgacure (R) 907 manufactured by Ciba Specialty Chemicals, Irgacure 369, or 2 -(3,4-Methylenedioxyphenyl) -4,6-bis (trichloromethyl) -1,3,5-triazine was used.

  When one or two or more photopolymerization initiators selected from the above are added, it is considered that the polymerization rate is high and the degree of polymerization is high, and it is excessively cured beyond the width (size) of the mask opening during pattern exposure. The pattern width after development is about 10 to 15 μm thicker than the mask opening width. On the other hand, when an opening mask of about 5 μm is used, the difference in film thickness between the portion immediately below the opening and the excessively hardened portion becomes remarkable, and the in-plane film thickness becomes nonuniform. Therefore, it is difficult to form a pattern width of 20 μm or less. In addition, since these photopolymerization initiators remain in the retardation material including the residue even after the reaction is completed, the transmittance of the retardation layer 38 is changed to visible light (visible light wavelength, wavelength in the range of 400 nm to 800 nm). It is difficult to make it 95% or more with respect to the light), usually 90% or less, and these coloring cannot be suppressed.

  On the other hand, the phosphine oxide-based photopolymerization initiator is known to have a photobleaching function, and since the coloration derived from the photopolymerization initiator does not occur, the transmittance of the retardation layer 38 is changed to visible light (visible light, 95% or more of light having a wavelength in the range of 400 nm to 800 nm), and coloring of the retardation layer 38 can be suppressed.

  In this embodiment, since the retardation layer 38 is made of a liquid crystal polymer, the liquid crystal layer 10 has higher molecular orientation than a conventional external retardation plate formed by stretching an organic polymer film. Have the same degree of orientation. Therefore, Δn of the retardation layer 38 is much larger than that of an external retardation plate, and can be made to be about the same as or higher than that of the liquid crystal layer 10 by appropriately adjusting the molecular structure and film forming conditions. The thickness of the external retardation plate is several tens of μm, which is nearly 10 times the thickness of the liquid crystal layer. However, if a liquid crystal polymer is used as the internal retardation layer, the layer of the retardation layer 38 is formed. The thickness can be significantly reduced, and the thickness can be made thinner than the step between the reflective display portion and the transmissive display portion. As a result, even if the retardation layer 38 is patterned in accordance with the reflective display portion, no special planarization is required.

  The transflective liquid crystal panel manufactured as described above was connected to a driving device, a backlight was placed behind the liquid crystal display device, and the display state was observed. When observed in a bright place with the backlight turned off, a display image by reflection display could be confirmed. Next, when the backlight was turned on and observed in a dark place, a display image by transmissive display could be confirmed. Even if the observation direction with respect to the substrate normal was changed in a wide range, gradation inversion did not occur and the contrast ratio did not decrease much.

  Moreover, in the liquid crystal display device of the said embodiment, there is no phase difference layer material with small adhesive force with the said sealing material between the sealing material and the 1st board | substrate 31. FIG. Therefore, the first substrate 31 and the second substrate 32 are firmly fixed, and the displacement and peeling of both the substrates due to the application of external force are avoided, and an all-environment type structure-solid display device is obtained.

  In the transmissive display portion TA of the transflective liquid crystal display device composed of the liquid crystal panel manufactured as described above, the transmission axis of the first polarizing plate 41 and the transmission axis of the second polarizing plate 42 are orthogonal, and the latter is Parallel to the alignment direction of the liquid crystal layer. Since this is the same configuration as that of the transmissive IPS system, a wide viewing angle that can withstand monitor applications can be obtained for transmissive display as in the transmissive IPS system.

  On the other hand, the reflective display portion RA includes a homogeneously oriented liquid crystal layer 10, a retardation layer 38, and a first polarizing plate 41. The relationship between the slow axis of the retardation layer 38, the alignment direction of the liquid crystal layer, and the transmission axis angle of the first polarizing plate 41 is as follows. That is, since the slit 30 of the pixel electrode 28 shown in FIG. 1 is perpendicular to the signal wiring 22, the electric field direction is parallel to the direction of the signal wiring 22. When the azimuth angle is defined counterclockwise, the alignment direction of the liquid crystal layer is −75 degrees with respect to the electric field direction, which stabilizes the alignment change during voltage application and reduces the borrowed voltage while the alignment change occurs. can get. The slow axis direction of the retardation layer 38 and the transmission axis of the first polarizing plate 41 are 67.5 degrees and 90 degrees, respectively, with respect to the alignment direction of the liquid crystal layer.

  Further, since the retardation of the liquid crystal layer 10 and the retardation layer 38 of the reflective display portion RA is set to a quarter wavelength and a half wavelength, respectively, in the reflective display portion RA, the liquid crystal layer 10, the retardation layer 38, The laminated body of one polarizing plate 41 becomes a broadband circularly polarizing plate. When no voltage is applied, the incident light is incident on the reflecting plate in a circularly polarized state or a polarization state close thereto in almost the entire visible wavelength range. When the light enters the first polarizing plate 41 again after reflection, the direction of vibration becomes linearly polarized light parallel to the absorption axis of the first polarizing plate, so that an achromatic dark display is obtained.

  The above formula (1) for determining the slow axis azimuth of the retardation layer 38 and the retardation of the retardation layer 38 and the liquid crystal layer 10 are derived as follows using Poincare sphere display. The Poincare sphere display is defined in a space having three axes of Stokes parameters (S1, S2, S3) describing the polarization state, and each point on the Poincare sphere corresponds to the polarization state on a one-to-one basis. For example, the intersection line (equator) with the (S1, S2) plane on the Poincare sphere corresponds to linearly polarized light, the intersection with the S3 axis (north and south poles) corresponds to circularly polarized light, and the rest corresponds to elliptically polarized light. To do. Further, (S1, S2, S3) are expressed by the following equations (2), (3), and (4) using an arbitrary X-axis component Ex and an arbitrary Y-axis component Ey of the electric vector, and the phase difference δ between Ex and Ey, respectively. expressed.

S1 = (Ex ² −Ey ² ) / (Ex ² + Ey ² ) (2)

S2 = 2ExEycos δ / (Ex ² + Ey ² ) (3)

S3 = 2ExEysinδ / (Ex ² + Ey ² ) (4)

  The conversion of the polarization state by the phase difference layer 38 and the liquid crystal layer 10 without shake is included in the (S1, S2) plane on the Poincare sphere, and is expressed as a rotation around a line passing through the center of the Poincare sphere. The rotation angle at this time is 1/2 rotation if the retardation of the phase plate is 1/2 wavelength, and 1/4 rotation if the retardation is 1/4 wavelength.

  Incident light having a typical wavelength in the visible light region, for example, a wavelength of 550 nm at which human visibility is maximized, sequentially passes through the first polarizing plate 41, the retardation layer 38, and the liquid crystal layer 10 of the reflective display portion RA. Attention is paid to the process of passing through and reaching the pixel electrode 28 or the common electrode 29.

  For the sake of explanation, if the Poincare sphere is simulated as a globe and the intersection with the S3 axis is called the north and south poles, and the intersection with the (S1, S2) plane is called the equator, the first polarizing plate 41 converts it into linearly polarized light. The incident light is located at the equator on the Poincare sphere, but the phase difference layer 38 causes the azimuth angle to make a half rotation about the rotation axis and move to another point on the equator, so that the linearly polarized light having a different vibration direction is obtained. Is converted to Next, the liquid crystal layer 10 rotates the azimuth by a quarter around the rotation axis and moves to the north pole, that is, is converted into circularly polarized light.

  Next, when attention is paid to incident light having a wavelength other than this, retardation has wavelength dependency, and the retardation is larger on the short wavelength side and smaller on the longer wavelength side in both the retardation layer and the liquid crystal layer. Therefore, the rotation angle varies depending on the wavelength, and light having a wavelength other than 550 nm moves to a point deviating from the equator without being halved in rotation by the retardation layer 38. Since the retardation of blue light on the short wavelength side is larger than ½ wavelength, it moves more than ½ rotation and moves to a position off the equator. Since the red light on the long wavelength side has a retardation smaller than ½ wavelength, the red light rotates smaller than ½ rotation and moves to a position off the equator.

However, since the movement direction is substantially opposite in the rotation by the liquid crystal layer 10 that acts next, the difference in the rotation angle due to the wavelength generated in the retardation layer 38 is compensated. That is, the blue light on the short wavelength side rotates more than ¼ rotation in the liquid crystal layer 10, but reaches just above the north pole because it starts moving from the southern hemisphere. The red light on the long wavelength side rotates in the liquid crystal layer 10 less than 1/4 rotation, but since it starts to move from above the northern hemisphere, it reaches just above the North Pole by rotating less than 1/4 rotation. As a result, light of each wavelength is concentrated in the vicinity of the North Pole, and light of each wavelength becomes substantially the same circularly polarized light. When this is observed as a display state of the liquid crystal layer, an achromatic dark display having a reduced reflectance in a wide visible wavelength region can be obtained.
When an auxiliary line is drawn so as to extend the quarter rotation direction, the auxiliary line is orthogonal to the liquid crystal layer alignment direction (azimuth angle θ′LC) representing the center of the rotation. Further, the slow axis direction (azimuth angle θ′PH) of the built-in phase plate representing the center of 1/2 rotation bisects the angle between the S1 axis and the auxiliary line. The angle tangent obtained by dividing the angle between the Sl axis and the auxiliary line into two equal parts, θ′PH−180 °, and θ′LC−180 ° is equal to (θ′PH−180 °) × 2 + 90 °. The following equation (5) is obtained.

      2θ′PH = 90 ° + θ′LC (5)

  In the above, incident light of each wavelength is concentrated on the North Pole NP on the Poincare sphere, but the same effect can be obtained by concentrating on the South Pole SP of the Poincare sphere. In this case, the relationship between θ′PH and θ′LC is expressed by the following equation (6).

      2θ′PH = −90 ° + θ′LC Formula (6)

  Furthermore, in order to concentrate the incident light of each wavelength on the north pole NP or the south pole SP, the relationship between θPH and θ′LC is expressed by equations (5) and (6), respectively. That is, since 360 ° −θ′LC is equal to (360 ° −θ′PH) × 2 + 90 °, 2θ′PH = 360 ° + 90 ° + θ′LC, which is expressed by Expression (5). Since 180 ° −θ′LC is equal to (180 ° −θ′PH) × 2 + 90 °, 2θ′PH = 360 ° −90 ° + θ′LC, which is expressed by Expression (6).

  The rotation axis on the Poincare sphere corresponds to the azimuth angles θPH and θLC of the slow axis, and the azimuth angle of the rotation axis is twice the azimuth angle of the slow axis in real space (θ′PH = 2θPH, θ′LC = 2θLC). By substituting this into the equations (5) and (6), the above equation (1) representing the relationship between the slow axis azimuth of the built-in phase plate and the hard crystal layer can be obtained.

  In the first embodiment, in order to make the viewing angle characteristic of the transmissive display equal to that of the transmissive IPS, the polarizing plate arrangement in the transmissive display unit TA is made the same as that of the transmissive IPS system. This made θLC = 90 degrees. Substituting this into equation (1) and selecting a minus sign results in θPH = 22.5 degrees, and the slow axis azimuth of the retardation layer is obtained. Note that details regarding the setting of the slow axis azimuth of the retardation layer described above are disclosed in Patent Document 3 and will not be described further.

  << Second Embodiment >>

  Next, a second embodiment of the present invention will be described.

  FIG. 4 is a cross-sectional view of a liquid crystal panel according to the liquid crystal display device of the second embodiment. This corresponds to a cross-sectional view taken along the line A-A 'of FIG. The liquid crystal display device of the present embodiment is different from the liquid crystal display device of the first embodiment with respect to the retardation layer 38. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  In the first embodiment, in order to form the retardation layer 38, a retardation layer forming material is applied to the entire surface of the third alignment film 37 on the planarizing layer 36, and reflection display is performed by mask exposure. Only the portion RA was selectively cured, and the uncured portion of the transmissive display portion TA was removed by organic development. On the other hand, in this embodiment, the uncured portion of the transmissive display portion TA is heated and cured without the phase difference. And it leaves as transparent layer 38n, without removing.

  FIG. 5 is a diagram showing a manufacturing process of the liquid crystal panel constituting the liquid crystal display device of the present embodiment.

  After the third alignment film 37 is formed on the entire surface of the first substrate 31, it is rubbed to give alignment control ability (P-2). The third alignment film 37 is horizontally aligned and has a function of determining the slow axis direction of the retardation layer 38.

  Next, a retardation layer material is applied on the third alignment film 37 (P-3). Here, as a retardation layer material, a polymerization initiator (reaction initiator) having a phosphine oxide structure is added to a nematic liquid crystal monomer having a photoreactive acrylic group (acrylate) at the molecular end, as in the first embodiment. ) Is used in an organic solvent.

  The liquid crystal monomer with an acrylate of the retardation layer forming material and the polymerization initiator having a phosphine oxide structure are as exemplified in the first embodiment.

  Here, the relationship between the polymerization initiator and the irradiated light will be described. The liquid crystal material for forming the phase difference layer 38 is usually colored when absorbing light having a wavelength of less than 300 nm. Therefore, it is preferable that light having a wavelength of less than 300 nm is not irradiated.

  Therefore, a lamp that can irradiate light of a specific wavelength is used. For example, it is desirable to use a black light blue fluorescent lamp (Black-light Blue (BL-B) Fluorescent Lamp). The black light blue fluorescent lamp mainly emits near-ultraviolet light (Near-ultraviolet Light, nominal wavelength band: 300 to 400 nm), and exhibits a peak wavelength of, for example, 360 nm.

  Alternatively, a filter that blocks light having a wavelength of less than 300 nm may be used. For example, a short wavelength cut ultraviolet filter that blocks short wavelength light can be used. In addition, a filter that cuts all absorption wavelengths of the liquid crystal substance forming the retardation plate may be used. As an example, Teijin Tetron Film G2 (trade name) manufactured by Teijin DuPont Film can be used.

  Thus, since the light of 300 nm or more is irradiated by selecting a lamp or a filter, the phase difference forming material needs to be cured by irradiation of light having a wavelength of 300 nm or more. Therefore, a photopolymerization initiator having absorption at 300 to 400 nm is selected. Preferably, it is a photopolymerization initiator whose extinction coefficient in methanol as a solvent is in the range of 1000 ml / g cm or more at 365 nm and 100 ml / g cm or more at 405 nm.

  As described above, the transmittance of the retardation layer 38 and the transparent layer 38n is changed to visible light (visible light, 400 nm to 800 nm) by appropriately selecting the material of the retardation plate, the photopolymerization initiator, and the wavelength of the irradiation light. Of light having a wavelength in the range of 95% or more), and these coloring can be suppressed.

  After applying the retardation layer forming material, this is pre-baked for 2 to 3 minutes with a hot plate at 100 ° C. to remove the solvent (P-4), thereby forming a transparent film. This film is oriented in the direction of the orientation treatment of the third orientation film 37 when pre-baked, and has a function as a retardation plate.

  The pre-baked retardation layer forming material is exposed to ultraviolet light (preferably as described above) in a portion corresponding to the reflective display portion RA using an exposure mask having an opening corresponding to the pattern of the retardation layer 38 to be formed. Are cut to a wavelength of less than 300 nm) to photopolymerize and cure the acrylic group to obtain a retardation layer 38 (P-5). By this mask exposure, the acrylate corresponding to the opening of the exposure mask is polymerized and functions as a retardation plate. At this time, the film concentration is adjusted by appropriately adjusting the solution concentration and the coating conditions at the time of coating so that the retardation of the retardation layer 38 becomes a half wavelength at a wavelength of 550 nm.

  Thereafter, the entire first substrate is heated to a temperature higher than the nematic / isotropic phase transition temperature of the liquid crystal monomer of the retardation layer forming material, thereby eliminating the retardation of the uncured portion corresponding to the non-opening portion of the exposure mask. Let By exposing the entire surface to a lamp in a heating state that eliminates the phase difference, the uncured acrylic group located in the non-opening portion of the exposure mask is photopolymerized and cured without any phase difference, thereby forming a transparent layer 38n. (P-6 ').

  The whole-surface exposure lamp may be an ultraviolet fluorescent lamp of about 20 W arranged in parallel, but a black light blue fluorescent lamp (Black-light Blue (BL-B) Fluorescent Lamp), which is one type thereof, is used. desirable. The black light blue fluorescent lamp mainly emits near-ultraviolet light (Near-ultraviolet Light, nominal wavelength band: 300 to 400 nm), and exhibits a peak wavelength of, for example, 360 nm.

  Since the retardation layer 38 is made of a liquid crystal polymer, the molecular orientation is higher than that of a conventional external retardation plate made by stretching an organic polymer film, and the same orientation as that of the liquid crystal layer 10. Have The transparent layer 38n is optically transparent and Δn is 0, but Δn of the retardation layer 38 located in the same layer is much larger than that of the external retardation plate, and the molecular structure and film formation By appropriately adjusting the conditions, the liquid crystal layer 10 can be made to have the same level or higher. The thickness of the external retardation plate is several tens of μm, which is nearly 10 times the thickness of the liquid crystal layer. However, if a liquid crystal polymer is used as the internal retardation layer, the layer of the retardation layer 38 is formed. The thickness can be significantly reduced, and the step between the reflective display area RA and the transmissive display area TA is eliminated.

  Next, a transparent organic layer is applied on the retardation layer 38 to form the second protective layer 40 (P-7). Next, a photosensitive transparent resist is applied to the second protective layer 40 and exposed to ultraviolet rays using an exposure mask. Here, patterning is performed using an exposure mask having a distribution similar to that of the reflective display portion. Thereafter, the film thickness adjusting layer 39 is formed only on the upper layer of the retardation layer 38 by alkali development (P-8).

  If the retardation layer 38 has a Δn larger than twice that of the liquid crystal layer, the thickness becomes insufficient when the retardation of the retardation layer 38 is ½ wavelength. The difference in retardation between the reflective display area RA and the transmissive display area TA is smaller than a quarter wavelength. Therefore, by forming a film thickness adjusting layer 39 on the retardation layer 38, a quarter-wave retardation difference is ensured between the reflective display portion and the transmissive display portion.

  A direction in which the first alignment film 33 is applied to the uppermost layer of the main surface of the first substrate 31 and the second alignment film 34 is applied to the uppermost layer of the main surface of the second substrate 32 so as to cross each other at a predetermined angle. After the rubbing process, a columnar spacer is interposed in the display area of the first substrate 31 and the second substrate 32 (P-9), a sealing material is applied to the inside of the outer peripheral edge, and the two substrates are bonded together for assembly. The liquid crystal layer 10 is sealed inside (P-10).

  Finally, the first polarizing plate 41 and the second polarizing plate 42 are respectively arranged outside the first substrate 31 and the second substrate 32 (P11). The transmission axes of the first polarizing plate 41 and the second polarizing plate 42 are arranged so as to be orthogonal and parallel to the liquid crystal layer alignment direction, respectively.

  The manufacturing process of the liquid crystal panel of the second embodiment has been described above.

  When a retardation layer forming material to which a phosphine oxide photopolymerization initiator is added is used as in this embodiment, the pattern width of the retardation layer 38 is about 3-5 μm thicker than the design value of the width of the mask opening. To be suppressed. Therefore, it is possible to make the pattern width maximum detail 20 μm or less. Then, the reproducibility of the photomask is improved, and high definition of the liquid crystal panel can be realized. Further, in the manufacturing process, the tolerance of the alignment accuracy at the time of pattern exposure is increased, and product defects due to the exposure misalignment are reduced.

  Here, the usefulness of the phosphine oxide photopolymerization initiator will be described using a comparative example. In the comparative example, as shown in the above “chemical formula 4”, a general-purpose photopolymerization initiator, for example, Irgacure (R) 907 manufactured by Ciba Specialty Chemicals, Irgacure 369, or Irgacure 369, or 2- (3,4-methylenedioxyphenyl) -4,6-bis (trichloromethyl) -1,3,5-triazine was used.

  When one or two or more photopolymerization initiators selected from the above are added, it is considered that the polymerization rate is high and the degree of polymerization is high, and it is excessively cured beyond the width (size) of the mask opening during pattern exposure. The pattern width after development is about 10 to 15 μm thicker than the mask opening width. On the other hand, when an opening mask of about 5 μm is used, the difference in film thickness between the portion immediately below the opening and the excessively hardened portion becomes remarkable, and the in-plane film thickness becomes nonuniform. Therefore, it is difficult to form a pattern width of 20 μm or less. In addition, since these photopolymerization initiators remain in the retardation material including the residue even after the reaction is completed, the transmittance of the retardation layer 38 is changed to visible light (visible light wavelength, wavelength in the range of 400 nm to 800 nm). It is difficult to make it 95% or more with respect to the light), usually 90% or less, and these coloring cannot be suppressed. Further, in this process, since the retardation layer made of the transparent layer 38n remains also in the transmissive display portion TA, the transmittance of the transmissive display portion TA due to coloring decreases (the transmittance is 90% or less at 400 nm).

  On the other hand, the phosphine oxide-based photopolymerization initiator is known to have a photobleaching function, and since the coloration derived from the photopolymerization initiator does not occur, the transmittance of the retardation layer 38 is changed to visible light (visible light, 95% or more of light having a wavelength in the range of 400 nm to 800 nm), and coloring of the retardation layer 38 can be suppressed.

  Moreover, since the phosphine oxide photopolymerization initiator is known to have a photobleaching function and coloring due to the photopolymerization initiator does not occur, the transmittance of the retardation layer 38 is set to be visible light (VisibleLlght, 400 nm). 95% or more of light having a wavelength in the range of 800 nm to 800 nm), and coloring of these can be suppressed.

  The transflective liquid crystal panel produced as described above was connected to a driving device, a backlight was placed behind the liquid crystal display device, and the display state was observed. When observed in a bright place with the backlight turned off, a display image by reflection display could be confirmed. Next, when the backlight was turned on and observed in a dark place, a display image by transmissive display could be confirmed. Even if the observation direction with respect to the substrate normal was changed in a wide range, gradation inversion did not occur and the contrast ratio did not decrease much.

  Further, in the liquid crystal display device of the present embodiment, there is no retardation layer material having a small adhesive force between the sealing material and the first substrate 31. Therefore, the first substrate 31 and the second substrate 32 are firmly fixed, and the displacement and peeling of both the substrates due to the application of external force are avoided, and an all-environment type structure-solid display device is obtained.

  The example of the embodiment of the present invention has been described above.

  According to the embodiment to which the present invention is applied, it is possible to carry a high-quality display device similar to a large monitor, and by using this for a display device of a mobile phone, high-quality image information can be reproduced. It becomes possible to handle more advanced image information. Furthermore, if it is used for a digital camera, it becomes easy to confirm an image before photographing and a photographed image. In the future, with the spread of terrestrial digital broadcasting, it is expected that the reception status of portable televisions will also improve significantly. However, if used in portable televisions, high-quality image information can be reproduced regardless of location. .

  Further, according to the present invention, excessive curing of the retardation layer forming material is suppressed, and pattern reproducibility close to the design value can be realized. As a result, the liquid crystal panel can be further refined, the alignment tolerance during pattern exposure in the manufacturing process is increased, and product defects due to misalignment are reduced.

  The liquid crystal display device of the present invention is an all-environment-type structurally robust display device capable of displaying in a variety of environments ranging from outdoor to darkroom in fine weather, and has a wide viewing angle display comparable to a monitor in transmissive display. Can be obtained.

  As described above, the invention of the present application is characterized by adding a photopolymerization initiator having a phosphine oxide structure to the liquid crystal monomer of the retardation material when the built-in retardation layer is formed. Such a method of forming a retardation layer can be applied to the production of various types of liquid crystal display devices having a built-in retardation layer. That is, the present invention is not limited to the IPS system, and can also be applied to the manufacture of liquid crystal display devices such as a TN (Twisted Nematic) system and a VA (Virtical Alignment) system that incorporate a retardation layer.

It is a top view explaining the structural example of 1 pixel of the liquid crystal panel of 1st Embodiment. It is sectional drawing along the A-A 'line of FIG. It is explanatory drawing of the manufacturing process of a liquid crystal panel. It is sectional drawing (A-A 'of FIG. 1) of the liquid crystal panel concerning 2nd Embodiment. It is explanatory drawing of the manufacturing process of a liquid crystal panel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Liquid crystal layer 21 ... Scanning wiring 22 ... Signal wiring 23 ... Common wiring 25 ... Amorphous silicon layer 26 ... Through hole 27 ... Through hole 28 ... Pixel electrode 29 ... Common electrode 30 ... Slit 31 ... First substrate (color filter substrate)
32 ... Second substrate (TFT substrate)
33 ... 1st alignment film 34 ... 2nd alignment film 35 ... Black matrix 36 ... Overcoat film 37 ... 3rd alignment film 38 ... Retardation layer 38n ... -Transparent layer 39 ... Film thickness adjusting layer 40 ... Flattening layer 41 ... First polarizing plate 42 ... Second polarizing plate 43 ... Adhesive layers 51, 52, 53 ... Insulating layer 61 ... Transmitted light 62 ... Reflected light

Claims (18)

A liquid crystal display device having a reflective display portion and a transmissive display portion,
A first substrate; a second substrate; a liquid crystal layer sandwiched between the first substrate and the second substrate;
A retardation layer is built in between the first substrate and the second substrate,
The retardation layer is
A liquid crystal display device formed by polymerizing an acrylated liquid crystal monomer using a photopolymerization initiator having a phosphine oxide structure. A liquid crystal display device having a reflective display portion and a transmissive display portion,
A first substrate, a second substrate, a liquid crystal layer, a first alignment film, a second alignment film, a third alignment film, a pixel electrode, a common electrode, a retardation layer, a retardation layer material layer, a sealing material, Having a first polarizing plate and a second polarizing plate;
The liquid crystal layer is held in a facing gap between the first substrate and the second substrate;
The first alignment film is provided between the liquid crystal layer and the first substrate, and the second alignment film is provided between the liquid crystal layer and the second substrate,
The pixel electrode and the common electrode are provided for each pixel on the main surface of the second substrate,
The reflective display portion and the transmissive display portion are provided for each pixel,
The retardation layer is provided on a main surface side of the second substrate and corresponding to the reflective display unit,
The sealing material circulates between the periphery of the first substrate and the second substrate to seal the liquid crystal layer,
The first polarizing plate is disposed on an outer surface of the first substrate;
The second polarizing plate is disposed on an outer surface of the second substrate;
The material for forming the retardation layer is
A liquid crystal display device formed by polymerizing an acrylated liquid crystal monomer using a photopolymerization initiator having a phosphine oxide structure. In claim 1,
The retardation layer is
A liquid crystal display device having a transmittance of 95% or more with respect to visible light (visible light, light having a wavelength in the range of 400 nm to 800 nm). In claim 1,
The retardation layer is
A liquid crystal display device, wherein the most detailed pattern is formed with a width of 20 μm or less. In claim 1,
The retardation layer is
A liquid crystal display device disposed between the first substrate and the liquid crystal layer. In claim 2,
The liquid crystal display device, wherein transmission axes of the first polarizing plate and the second polarizing plate are arranged orthogonal to each other. In claim 6,
One of the transmission axis of the first polarizing plate and the transmission axis of the second polarizing plate is arranged in parallel to the alignment direction of the liquid crystal layer. In claim 1,
The retardation of the liquid crystal layer of the reflective display unit is a quarter wavelength,
The retardation of the phase layer is a half wavelength, and the liquid crystal display device. In claim 2,
The liquid crystal layer is homogeneously oriented;
The transmission axis of the first polarizing plate is parallel to the alignment direction of the liquid crystal layer,
The slow axis azimuth angle of the retardation layer is 20 degrees or more and 25 degrees with the transmission axis of the first polarizing plate.
A liquid crystal display device characterized in that it is either less than 60 degrees or 60 degrees or more and 75 degrees or less. In claim 1,
A liquid crystal display device comprising a film thickness adjusting layer above the retardation layer. In claim 10,
A liquid crystal display device characterized by covering the retardation layer and having a protective film made of a transparent resin under the film thickness adjusting layer. A method of manufacturing a liquid crystal display device having a reflective display portion and a transmissive display portion,
The liquid crystal display device
A first substrate; a second substrate; and a liquid crystal layer sandwiched between the first substrate and the second substrate,
A retardation layer is built in between the first substrate and the second substrate,
The manufacturing method includes:
The manufacturing method of the liquid crystal display device characterized by including the process of forming the said phase difference layer using the liquid crystal monomer with an acrylate, and the photoinitiator which has a phosphine oxide structure. A liquid crystal layer is held in a facing gap between the first substrate and the second substrate, and the first substrate and the second substrate are sealed at the outer peripheral edge of the display region by a sealing material. Is a method of manufacturing a liquid crystal display device, which is composed of a matrix arrangement of a plurality of pixels and has a reflective display portion and a transmissive display portion for each pixel,
Forming a retardation layer alignment film on the main surface of the first substrate, and imparting an alignment control ability to the retardation layer alignment film;
A retardation layer material application step of covering the retardation layer alignment film and applying a photocurable acrylated nematic liquid crystal monomer to which a photopolymerization initiator having a phosphine oxide structure is added as a retardation layer material;
An exposure step of selectively exposing and curing a portion corresponding to the reflective display portion of the retardation layer material;
A method of manufacturing a liquid crystal display device, comprising: an unexposed portion removing step of removing a portion corresponding to the transmissive display portion of the retardation layer material. A liquid crystal layer is held in a facing gap between the first substrate and the second substrate, and the first substrate and the second substrate are sealed at the outer peripheral edge of the display region by a sealing material. Is a method of manufacturing a liquid crystal display device, which is composed of a matrix arrangement of a plurality of pixels and has a reflective display portion and a transmissive display portion for each pixel,
Forming a retardation layer alignment film on the main surface of the first substrate, and imparting an alignment control ability to the retardation layer alignment film;
A retardation layer material coating step for coating the retardation film for the retardation layer and applying a photocurable acrylated nematic liquid crystal monomer to which a photopolymerization initiator having a phosphine oxide structure is added as a retardation layer material;
An exposure step of selectively exposing and curing a portion corresponding to the reflective display portion of the retardation layer material;
A step of heating an unexposed portion, which is a portion corresponding to the transmissive display portion of the retardation layer material, to a temperature equal to or higher than a nematic isotropic layer transition temperature to be transparent, and curing by irradiation with light in a heated state. A method for manufacturing a liquid crystal display device. In claim 13,
The manufacturing method of the liquid crystal display device characterized by including the process of forming a film thickness adjustment layer in the upper layer of the said phase difference layer. In claim 14,
The manufacturing method of the liquid crystal display device characterized by including the process of forming a film thickness adjustment layer in the upper layer of the said phase difference layer. In claim 15,
A method for manufacturing a liquid crystal display device, comprising: a step of covering the retardation layer and a residual layer of a material for forming the retardation layer and forming a protective film made of a transparent resin under the film thickness adjusting layer. In claim 16,
A method for manufacturing a liquid crystal display device, comprising: a step of covering the retardation layer and a residual layer of a material for forming the retardation layer and forming a protective film made of a transparent resin under the film thickness adjusting layer.

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